Contact transfer for xerography



May 12, 1959 w. G. VAN DORN, 6

' CONTACT TRANSFER FOR XEiROGRAPl-IY Filed Aug. 9, 1955 2 Sheets-Sheet 1INVENTOR. WARREN G. VAN DORN BYF l ATTORWY May 12, 1959 w. G. VAN DORN6,

, CONTACT TRANSFER FOR XEROGRAPHY Filed Aug. 9, 1955 2 Sheets-Sheet zINVENTOR.

WARREN e. .VAN DORN ATTQPNEY United States Patent 2,886,464CONTACTTRANSFER FOR XEROGRAPHY Warren G. Van Dorn, Columbus, Ohio,assignor, by mesne assignments, to-Halo'id ,Xerox Inc., a corporation ofNew York Application August 9,1955, Serial No. 527,354 4 Claims.117-175) This inve'ntionrela'testo xerography, and in particular to thetransferof electrOScopic particles used in the developing process.

In the art of .xerography as disclosed in Carlson Patent No. 2,297,691,it is usual toplace an electrostatic charge on a xerographic memberwhich is generally composed of a. photoconductive layer overlying aconductive backing. This charged member is then exposed to copy to bereproduced and the electrostatic charge on the photoconductiveinsulating layer is selectively discharged, thereby leaving anelectrostatic latent image on the photoconductive surface. This latentimage nay then be developed by depositing thereon electroscopicparticles carrying charges opposite tothose composing the electrostaticlatent image. Thesecharged particles adhere to areas of chargeon-theinsulatinglayer, thereby developing an electrostatic imagepattern. This. image pattern may be utilizedvas itexists on the surfaceof the insulating layer, or it may. be. transferredto other materials.This invention dealsprimarily with. methods, means and apparatus oftransfer which improve upon past processes of transfer, and particularlywith a new material for such methods, means and apparatus.

One of the usual methods of transfer is to cause particles ofelectroscopie material to move. from the insulating surface to anothersurface by the use of externally applied. electrostatic forces. Anotheris to apply adhesive to. the transfer sheets and rely uponadhesion ofpowder tothe transfersheets. for transferof the developed image thereto.This invention. is concerned with new techniques of transfer includingthe .use of new. transfer materials and contact transfer in substitutionfor prior art transfer procedures.

Advantages. of the new. techniques are the ability to bring about abetter transfer and'so, as an end result, a finer xerographicreproduction than if the usual electrostatic or adhesive types oftransfer were, used. For example, more of the developerparticles areremoved from the insulating surface of the xerographic plate to thetransfer surface when the. techniques and transfer materials. of thisinvention are utilized as compared with the usual transfer techniquesnoted. above. This transfer of more developer particles is of particularvalve in many important instances where the image is not excessivelydense. Another object, therefore-of this invention is to provide newtransfer materials for these means, methods and apparatus to producefiner and more accurate and faithful xerographic transfers.

Further objects and. features of. the invention are to providexerographic transfer-materials which are highly effective in producingfaithful images of high resolution.

Further objects andfeatures of the presentinvention are to providexerographic transfer materials suitable for methods, means and apparatusof transfer of xerographic images onto. a transfer surface by contactand pressure, and in which the transfer surfaces do not haveconventional adhesive properties previously thought necessary foreffecting efficient transfers.

As further objects and features, this invention contem- "ice 2 platesthe utilization of resins overcoated onto a different resinous basecoating on paper or some other backing material to provide a desirabletransfer surface onto which the image on the xerographic elementmay-beelfectively transferred by contact under .pressure.

The base. coating according =to.the practice 'ofthis invention isa'resin material adapted to be compatible both with the support base andthe overcoating resin. Its physical properties are selected-so as toassurea of softness and ready deformation under stress in the layer. Itis the ready deformation of this base coating of resin under thepressure exerted upon it during transfer that permits the overcoatingresin to contact the developer particles of the image more uniformlyover the whole area of contact between the overcoating resin and thephotoconductive xerographic member at relatively low transfer forces(compared with contact transfer materials or members without such a basecoating).

Resins presently found suitable for overcoating resins of the inventionare polyethylenes of low molecular weight and polyamides of' mediummolecular weight. These resins are available commercially, onepolyethylene, Bakelite DYGT, a product of'the Bakelite Company of NewYork and one polyamide, General Mills Polyamide 94, a product of GeneralMills, -Inc., of Minneapolis, Minnesota, having been utilizedefiectively in the practice of this invention.

Base coating resins found suitable are natural or synthetic rubbermaterials. One particularly suitable such material is a polyisobutylenewhich is commercially available under the name Vistanex 153-100, aproduct of the Enjay Company, Inc., New York, New York. V istanex B-lOOhas been utilized as a base coating resin both alone and also as a blendwith Bakelite DYGT, a polyethylene herein named as an overcoating resin.Bakelite DYNH, a polyethylene of high molecular weight and a product ofthe Bakelite Company, New York, New York, also has been utilized as abase coating resin.

Where the overcoating resin is a polyethylene, suchas Bakelite DYGT, abase coating ofany one of the follow ing three materials may be utilizedin practice .of this invention: a polyisobutylene, such as VistanexB-lOO, a blend of a polyethylene, such as Bakelite DYGT, with apolyisobutylene, such as Vistanex B .l,00, and a polyethylene, such asBakelite DYNH. Where the overcoating resin is a polyamide, such asGeneral Mi1ls-Polyamide-94, the base coating resin may be a syntheticrubber, such as Vistanex polyisobutylene 13-100.

In practicing the invention, base-material such as papers which arecoated with the resins of the types herein mentioned preferably arewhite papers such as baryta papers ordinarily used as base stock ofphotographic papers, or similar white papers that will-receive andretain a coating of the resins mentioned. An example of such similarwhite papers is a high quality printing paper (regular printing, notphotographic printing) which has a smooth, glossy finish and whichgenerally is a clay coating with a casein binder. Such paper is knowncommercially as Kromekote paper, a product of The Champion PaperandFibre Company, Hamilton, Ohio.

The transfer members used for practicing the invention are prepared bycoating one of the papers mentioned with the base or undercoating resinand subsequently with the overcoating thermoplastic resins of thecharacter mentioned and thereafter efiecting contact transfer to suchtransfer members by use ofcontrolled amounts of pres sure. Acharacteristic feature of the transfer members is that adhesion, as such,is not a characigep'istic relied upwing iteesean thema W1... Otherobjects and fea'ug es of; hi; tionmill hecgme apparent mm the as panyingdrawings, wherein:

ber, generally designated as 10, is shown. The transfer member isgenerally composed of a two layered thermbplastic resin coating 11a and11b on a base material 12. 'The'base coating 11a generally is one of theresins hereinbefore mentioned, such as a natural rubber or synthetic'rubber material, a polyethylene material or the like. It ischaracterized by sponginess or compressibility (ease of deformationunder light or moderate pressure) to cause the composite member to bemore readily adapted to receive image material and is compatible withthe .overcoating 11b. Generally, the coating 11b is one of thethermoplastic resins mentioned, or a combination of such resins that haslow melt viscosity, which property is desirable and necessary only topermit the heat fixing of-a transferred image in the coating and whichcoating has very little, if any, tackiness at ordinary room temperatures(6080 F.). In addition, these resins generally have melting pointsbetween 150 F. and 300 F., or at least below the decompositiontemperature of the base material 12 used. Included in the group ofthermoplastic resins meeting these requirements are polyethylenes,polyamides, polystyrenes and other resins of the kind hereinabovespecifically mentioned. Also included are other thermoplastic resinshaving characteristics meeting the foregoing requirements.

Any material capable of being coated with a resin of the character.described is a suitable base material 12. This includes (but is in noway limited to) paper, film, glass, cloth, synthetic materials, and thelike. A preferred type of base material 12 is white paper such as barytacoated paper similar to the base stock of photographic papers. Includedare 5.5 mil, 3.5 mil, and other baryta coated papers of intermediatethicknesses. In practice, the preferred paper is 5.5 mil baryta coatedpaper which is whiter and less apt to wrinkle during transfer than otherpapers. Furthermore, the baryta surface of paper is very smooth'andapparently prevents bubblingof the resin of the coating 11 that may beencountered when other papers are used.

One arrangement for preparing a transfer member 10 is illustrateddiagrammatically in Figs. 2 and 3. Therein a sheet 12 of base materialis stretched taut b-y fastening its corners to a frame 19 positionedvertically over a shallow pan, tray or container 20. A liquid solution21 of the resin in appropriate solvent is poured from a container 22onto the vertical sheet 12 and allowed to flow down its surface. Theexcess or runoff liquid is collected in the pan 20 for re-use. It ispreferable when applying the solution 21 to effect an even number ofcoatingsby pouring the solution over sheet 12 alternately from itsopposite ends. The frame 19. is inverted after each pouring. Thisprocedure produces more uniform thickness of the coatings as comparedwith a single pouring of the solution.

The coated sheet is then dried. For example it may be deposited on aplate 23 heated by an appropriate heating device 24 to a controlledtemperature ranging from approximately 60 C. to 80 C. to evaporate thesolvent in the coating on sheet 12. In the alternative, radiant heat maybe directed against sheet 12 to evaporate the solvent. Next, thebase-coated sheet is similarly coated with the overcoating resin. Theresulting product is the transfer member 10 of Fig. 1 in which the resincoatings 11a and 11b are smooth and uniform and range in thickness fromabout .4: mil to 1' mil, or any other desired thickness depending upon*the number of pourings and the concentration of the solution used.

Other methods of applying the resin coatings to the sheet 12 of basematerial may be utilized. A conventionally known extrusion laminationprocess commonly utilized commercially for applying coating to basesheet material may be utilized in preparing the transfer member 10. Themethods of transfer member preparation described herein are merelyexemplary and are not to be construed as being included by way oflimitation.

A transfer member 10 provided as hereinabove described or in other waysmay have developed xerographic image patterns of a xerographic plate orelement transferred to it in a manner now to be described.

A developed xerographic image is composed of many small particles whichremain in position due to electrostatic forces. Often they are locatedon the original xerographic plate element. However, they may be onanother surface,v as for example, one to which they have beentransferred through theme of electrostatics. Either while on an originalplate or on such a surface where they are held in place due toelectrostatic forces, they may be transferred to a thermoplastic resincoated transfer member 10 of this invention.

To effect such transfer, the member 10 is placed with its resin coating11 including both coating 11a and coating 11b against the developedxerographic image 25 carried on an image bearing surface 26 of forexample a xerographic plate 27, as is shown in Fig. 4. These assembledcomponents are deposited on a transfer table 28 and the surface 26 andthe transfer member 10, while in contact are firmly pressed togetherbetween pressure and driven rolls 29 and 30 to cause the image body 25to be pressed on and attached to the coating 11 of the transfer member10. The amount of pressure used at the rolls will depend on many factorsas', for example, the height of the raised image 25, the thickness ofthe coating 11 and of the base material 12 and the like.

One means of exerting the pressure is shown in Fig. 4. The pressure rollshaft 31 is supported by a lever arm 32 which is fulcrumed at 33 from asupport member 34- carried by the base 28. Selected weights 35 ofdetermined amounts are suspended from the lever arm 32 to exert pressureon roll 29 toward roll 30 in an amount sufficient to press the raisedimage 25 onto the resin surface 11 of the transfer member" 10 when thelatter and the xerographic plate 27 pass between rolls Hand 30. Thepressure exerted by roll 29 may be varied by changing the number andsize of the suspended weights 35. Other means for exerting and varyingthe pressure may be employed. The rolls 29 and '30 may be composed ofmany substances, for example, steel.

Pressure also may be applied by manually rolling a rubber covered rolleracross the assembly of the transfer member and the image carryingsurface lying on a flat table. However, in such event great care must beexercised to apply uniform pressure during rolling because unevenpressures may bring about uneven transfers of the xerographic imagepattern 25 to the transfer sheet and thus poor reproduction oftheoriginal image. In general, a mechanized application of pressure ispreferable because of the uniformity of pressure that can be exerted.

After pressure has been applied as described, the trans fer member 10 isremoved from contact with the surface 26 and will carry on its resinlayer 11 the image pattern 25. At this point transfer is complete.

The transfer member 10 may then be subjected to further treatment topermanently fix the image 25 thereon. For example, the transfer member10 bearing the image 25 on its resin coating 11 may have the transferredimage 25 heat fixed to it as by heating the member 10 until the resincoating melts and absorbs all the powder of the transferredimage 25.,The heating is followedby cool .spreparationand the utilization for thetransfer of images of transfer; members, oftenwreferred to as doublecoated ortwoelayer'constructionxtransfer members, which in generalconsistjof apaper- :basematerial on which is coated a baselayer orcoatingof one of the resins or resinous materials; herein named assuitable base coating resins, over whichsisacoated a layer of one oftheresins ;.or resinous materials herein named as overcoating resins:

Base paper 12:

Type 1Baryta-coated. Thickness 3.5 to 5.5 mils. Method of applying bothcoat- Solution. rings 11a and 11b 0.10 to 1.0 Thickness of base coating11a to 0.10 to 1.0 mil. base paper 12 Stainless steel.

Thickness of overcoating 11b 6 inches. Transfer roll 29:

Material 0.75 inch. Length 60 to 300 pounds. 'Diameter to 50 pounds perForce :applied linear inch of roll Equivalent pressure length. Velocityof transfer member 10 'duringiimage transfer 2 'to 4 inches-per second.

Examples Example I.-Baryta coated papers ranging in thickness from 3.5mils' -to 5.5 mils were precoated with polyisobutylene as follows: 1

*A polyisobutylene composition available as herein described under thename of'Vistanex B-100 was dissolved in 'trichloroethyle'ne to form asolution containing about 3' to 10 percent by weight of thepolyisobutylene. The polyisobutylene is slowly and difficultlysolubleand preparation in relatively concentrated solution is timeconsuming. Acoating of this material was placed on the baryta-paper by the solutionmethod of Fig. 2 (and dried by removing the solvent by means of aradiant heat source) to produce relatively uniform polyisobutylenecoatings ranging from A to 3 mils in thickness. Because of the slow rateof solution of the polyisobutylene in the solvent, the thus coated paperwas adapted to receive a second (coating) or overcoating (of a differentresinous material) by solution methods without substantial removalor-distortion of the polyisobutylene undercoating. The thus precoatedpapers were coated again by the solution method of Fig. 2 with a 3 to 10percent by weight solution of low molecular weight (7000) polyethylene(Bakelite DYGT) intrichloroethylene, the solution being heated above 60C.'to produce coated paper sheets-with smooth, uniform overcoatings ofpolyethylene about /a mil to 1 mil thick. The polyethylene solutionpoured over the sheets of paper gelled almost immediately as it cooledbelow 60 C. The coated sheets then were heated in the apparatus of Fig.3 at a temperature of from 60 C. to 80 C. (or by means of radiant heatsource) to evaporate the solvent of the coatings.

Transfer members 10 produced as just described were then utilized totransfer an image 25 thereto by the method and means of Fig. 4. Duringtransfer pressures on the roll 29 of approximately 10'to 100 pounds perlinear inch of transfer'roll length were employed. Velocity'of theassembly during transfer was from 2 to 4 inches persecond. Subsequently,the transferred image was: fixed to the transfer 1 members. '10 byheating'the curved surface 40 to. approximately 250 10.700 Fnand drawingthe transfer members 10 across said surfaceat a rate of from 2 to 6inches. per second. Thus, the fixation time (of for example, a 4 inchby.4 inch image area) is of the order of a few seconds or less. Highertempera- V tures or larger surface area of contact betweenv the transfermember and heating surface will; decrease fixing time, while relativelythicker coatings on thicker paper require morefixing time. This isreferred to as heat 'fixing of images by conduction.

Images transferred to transfer members. l'flalso were heat fixedconveniently by radiation, wherein a transfer member bearing an imagewas moved. across and a few inches. away from the opening of the radiantheat source at a rate .of-from l. to 3 inches per second.

.Baryta papers provided with relatively thin polyethylene overcoatings,i.e., less. than lmilthick, were found to. produce verydesirable-results.

There is, however, alowerlimit .to .theuseful thickness of polyethylenecoatings when .utilized' as overcoatings on a base coatingof..polyisobutylene' Vistanex B-100 alone on a base material of paper.When the polyethylene overcoating is made too thin, there. isinsufiicient material to cover the-inherently adhesive surface of thepolyisobutylene base coating, so that in such acase a very thinpolyethylene overcoating may begin to show some tackiness, 'inthe senseof adhesive power. The use of such atransfer member then no longerinvolves the principle and method of contact transfer to transfer animage, but would involve the method of adhesive transfer and with it thedisadvantages inherent with all adhesive transfer materials.

In one instance a baryta coated base paper 3.5 mils thick base coatedwith 1.0. mil of Vistanex B-lOO polyisobutylene with 0.2 mil of 7000molecular weight polyethylene (Bakelite DYGT) produced satisfactorytransfer' with a pressure ofv25 pounds per linear inch applied to a baresteel roll /s of an inch in diameter and 6 inches in length. Velocityduring transfer was about 2 inches per second. Heat fixation of theimage was-effected by passage of the image in front of a radiant heaterat a velocity of Zinches per second.

Example II.-'Baryta paper 5.5 mils in thickness was first base coatedtow a thickness of A milwith a blend of resins consisting of percent byweightpolyisobutylene Vistanex B- with 10 percent by weight polyethyleneBakelite DYGT by the solution coating method of Fig. 2 followed byradiant heat drying. This precoated paper was then coated again by thesolution method with polyethylene Bakelite DYGT to a thickness of a miland radiant heat dried. The double coated transfer member so producedwas utilized to transfer an image 25 thereto by the method and means ofFig. 4 using a bare stainless steel transfer roll 29, 1% inches indiameter and 6 inches in length under a force of 300 pounds, which is 50pounds pressure per linear inch of roll length. The satisfactorytransfer that resulted was fixed by the radiant heat fixing method.

Example III.-The procedure of Example II for base coating andovercoating baryta paper- 3.5 mils in thickness was repeated. In thisinstance, however, pure Vistanex B-lOO polyisobutylene 3 /2 mils inthickness was used as the base coating and a /2 mil coating of GeneralMills Polyamide 94 was used as the overcoating resin.

A satisfactory image transfer resulted by utilizing this transfer memberby the method and means of Fig. 4, wherein a bar stainless transfer roll29, which was 6 inches in length and inch in diameter, was utilizedunder a force of pounds or 25 pounds per linear inch of transfer rolllength. Radiant heat fixing of the image resulted in a satisfactorilyfixed image with a relatively hard and glossy surface.

Example lV.--On the basis of other experimental work, wherein Barytapaper was coated only with a blend of high molecular weight polyethyleneand microcrystalline wax in which the polyethylene and the wax wereblended in the proportions of approximately 60 percent by weight ofpolyethylene and 40 percent by weight ofmicrocrystalline wax andutilized as a transfer member, it is proposed to coat a polyisobutylenebase coated baryta paper with a A to a /2 mil coating of a blend of ahigh molecular weight polyethylene, such as Bakelite DYNH and a refinedmicrocrystalline wax in the proportions of 60 percent by weight of highmolecular weight polyethylene and of 40 percent by weight of refinedmicrocrystalline wax. It is believed that a. transfermember of suchcomposition will be substantially equal in performance to transfermembers prepared according to Examples I, II, and 111.

Although in many respects this invention resembles transfer of theadhesive type, in actuality it differs therefrom since the transfercoating surface 11 has substantially no adhesive properties at usualroom temperatures. With adhesive transfer, particles of the imagepattern are retained by actual adhesion to the tacky surface. In thepractice of this invention, however, the electroscopic particles of theimage pattern appear to become attracted .to and held on the resinouscoating 11 of transfer member by means of an electrostatic force ofattraction possibly generated by friction or contact while under thepressure exerted during the transfer step.

It appears that the image particles are transferred in this manner inthe practice of this invention rather than by the phenomenon of trueadhesion.

With adhesive transfer, often the adhesive coating of a transfer memberwill adhere to the developed image bearing surface rather than to thebase material of the transfer member and create breaks or holes in thefinal product. With transfers of the instant invention, this problemdoes not exist. Where adhesive transfer surfaces are utilized, theyfrequently flake ofi the photoconductive layers of xerographic elementsduring transfer steps by adhesion. This problem likewise does not occurwith the practice of the instant invention where contact transfer iseffected.

This invention is of particular value where high quality reproductionsare required, for example, in continuous tone xerography. The presentlypreferred developed continuous tone image often may be of low densityand the transfer of such an image must be substantially complete. Toproduce a valuable final product in the case of continuous tone images,substantially all of the developed image must be transferred, and theparticles making up the image must remain in their proper positions onthe transfer material. This is accomplished by practicing the instantinvention.

It is apparent that in practicing the instant invention a preferredtransfer member embodies a paper base material provided with a coatingof a resin or resinous material that is readily deformable, whichdeformation is preferred to be elastic rather than plastic, under thepressure exerted upon it during image transfer, said coating referred toas the base coating itself is provided with an overcoating, of a resinor resinous material of different composition than the base coating,said overcoating having very little if any tackiness or adhesive powerat usual room temperatures of from 60 to 80 F., said base coating andovercoating materials having properties to permit ready coating of themupon paper to thicknesses ranging from a fractional mil to several mils.

The resinous coatings of the transfer member may be applied totransparent or translucent base materials instead of paper where badgesor similar articles are to be manufactured. Where the base material isone of the papers herein mentioned, whiteness, brightness and smoothnessof the product are noteworthy attributes.

The image transferred according to the practices of this inventiomnamelyby the method of contact transfer and utilizing double coated transfermaterials can be rendered (i.e. caused to become) a permanent image byvarious means of fixing. A preferred method or means is that of heatfixing. Thus by utilizing thermoplastic resinous materials asovercoating materials in the preparation of double coated transfermembers, images transferred to the surface of such thermoplasticovercoatings may be fixed permanently, rapidly and conveniently byheating such an overcoating to and usually slightly above its fusingtemperature whereupon the image particles are absorbed by theovercoating and are held rigidly upon cooling and solidification of theovercoating. Thermoplastic resinous materials, such as those resinousmaterials described herein as satisfactory in practicing of thisinvention generally have fusing temperatures within the range of 150 F.to 300 F. or other temperatures at least below the decompositiontemperature of the base material used, for example paper. The image sofixed by heat is a permanent image. An overcoating of a thermoplasticresin material herein described provides a reasonably hard glossytransparent and permanently finished surface in which the powderparticles are embedded and fixed. The surface is relatively hard ascompared with latex or gelatin or tacky compound surfaces and is longlasting and wear resistant. While there is no apparent necessity forovercoating the transferred image with spray fixatives or otherprotective coverings as means of fixing the image, such means of fixingand others may be utilized if they may be found advantageous insatisfying the end use requirements of present and proposed applicationsof xerography, that may involve the transfer and fixing of images,especially continuous tone images. As an example of still other means offixing that may be utilized, an image, transferred to the surface of adouble coated transfer member provided with an overcoating of such aresinous material as General MillsPolyamide 94, has been found to befixed satisfactorily in a matter of seconds at the usual roomtemperatures by subjecting the image bearing surface of such a transfermember to an atmosphere of saturated solvent vapor.

While specific materials, namely thermoplastic resins for use as baseand overcoating resins, have been described herein as useful inpracticing of this invention, there is no intention, therefore, oflimitation to the class of resins generally referred to as thermoplasticresins.

The thermoplastic property of a resin is of interest and advantage onlyin respect to offering a convenient and rapid method of fixingpermanently an image of electroscopic particles transferred to theresinous surface of a material, herein referred to as a transfer member,by heating the resinous surface to its fusing temperature, whereupon theimage particles are absorbed by the resinous coating and are fixed inplace permanently upon cooling and solidification of the resinouscoating.

Whether or not a resinous component of a transfer I member isthermoplastic, is not to be construed as afiecting the practice of thisinvention in respect to either the preparation of transfer members,consisting of a base coating of a resin on a support material whichcoating is then overcoated with a different resin, or the utilization ofsuch transfer members in receiving images of electroscopic particles bythe method herein described as contact transfer.

In preparing and utilizing transfer members, the use of resins, whichmay be rendered less thermoplastic or even completely nonthermoplasticby means of various agents, such as heat, light, chemicals and nuclearradiation, either before or after the transfer of electroscopic imageparticles to the surface of such a transfer member, is consideredpossible and is contemplated.

Thus the utilization of thermoplastic resinous materials as overcoatingmaterials in the construction or preparation of double coated transfermembers is advantageous in the practice of this invention in so far assuch materials have the noteworthy attribute of acting both as an imagethe need-=for any -auxiliary materials by. applicationof merely twoforms of energy, namely pressure energy-for image transfer and heatenergy for image fixation.

While. specific methods, means and examples of materials useful inpracticing the invention have been described herein, variations in anyor all thereof within the scope of the appended claims are possible andare contemplated. There is no intention, therefore, of limitation to theexact details of disclosure as herein made.

What is claimed is:

1. In the xerographic process comprising placing an electrostatic chargeon the surface of a photoconductive insulating layer, exposing theelectrically changed photoconductive insulating layer to a pattern oflight and shadow to be reproduced to create thereon an electrostaticimage corresponding to the pattern of light and shadow, contacting theelectrostatic image with electrostatically charged powder particles tocreate on the photoconductive insulating layer a deposit of powderparticles corresponding exactly to the electrostatic image andtransferring the powder image in image configuration to a transfermember, the improvement comprising afiectingltransfer of the powderimage by providing a transfer member comprising a base sheet coated withan elastically deformable resinous interlayer overcoated with a resinousmaterial substantiaHy non-tacky at room temperature selected from thegroup consisting of polyethylene and polyethylene blended with wax,contacting the resin coating of said transfer member with the powderimage on a photoconductive insulating layer and pressing said coatingand image together to thereby transfer said powder image to said resincoating at substantially room temperature and removing said base memberwith its coating from contact with said photoconductive layer wherebytransfer of the powder particles in image configuration is achievedwithout the necessity of depositing electrostatic charges on saidtransfer member, the pressure producing said transfer beingsubstantially less than that needed when the transfer member omits saidinterlayer.

2. In the xerographic process comprising placing an electrostatic chargeon the surface of a photoconductive insulating layer, exposing theelectrically charged photoconductive insulating layer to a pattern oflight and shadow to be reproduced to create thereon an electrostaticimage corresponding to the pattern of light and shadow, contacting theelectrostatic image with electroist-atically charged powder particles tocreate onthe photoconductive insulating layer a deposit of powderparticles corresponding exactly to the electrostatic image andtransferring the powder image in image configuration to a transfermember, the improvement comprising affecting transfer of the powderimage by providing a transfer member comprising a base sheet coated withan elastically deformable rubber interlayer overcoated with a resinousmaterial substantially non-tacky at room temperature selected from thegroup consisting of polyethylene and polyethylene blended with themicrocrystalline wax, contacting the resin coating of said transfermember with the powder image on a photoconductive insulating layer andpressing said coating and image together to thereby transfer said powderimage to said resin coating at substantially room temperature andremoving said base member with its coating from contact with saidphotoconductive layer whereby transfer of the powder particles in imageconfiguration is achieved without the necessity of depositingelectrostatic charges on said transfer member, the pressure producingsaid transfer being substantially less than that needed when thetransfer member omits said interlayer.

3. In the xerographic process comprising placing an electrostatic chargeon the surface of a photoconductive insulating layer, exposing theelectrically charged photoconductive insulating layer to a pattern oflight and shadow to be reproduced ...to. ..create"::thereonelectrostatic image correspondingto.the..pattern of l ightand shadow,contacting .the electrostatic image with" electrostatically chargedpowder particles to create on the photoconductive insulating layer adeposit of powder particles corresponding exactly to theelectrostatic-image and transferring the powder image in imageconfiguration to-a transfer member, the improvement comprising affectingtransfer of the powder image by providing a transfer member comprising abase sheet coated with an elastically deformable polyisobutyleneinterlayer selected from the group consisting of polyisobutylene ofrelatively high molecular weight and a blend of a polyisobutylene ofrelatively high molecular weight with a polyethylene of a relatively lowmolecular weight, said interlayer being overcoated with a resinousmaterial substantially nontacky at room temperature selected from thegroup consisting of polyethylene and polyethylene blended withmicrocrystalline wax, contacting the resin coating of said transfermember with the powder image on a photoconductive insulating layer andpressing said coating and image together to thereby transfer said powderimage to said resin coating at substantially room temperature andremoving said base member with its coating from contact with saidphotoconductive layer whereby transfer of the powder particles in imageconfiguration is achieved without the necessity of depositingelectrostatic charges on said transfer member, the pressure producingsaid transfer being substantially less than that needed when thetransfer member omits said interlayer.

4. In the xerographic process comprising placing an electrostatic chargeon the surface of a photoconductive insulating layer, exposing theelectrically charged photoconductive insulating layer to a pattern oflight and shadow to be reproduced to create thereon an electrostaticimage corresponding to the pattern of light and shadow, contacting theelectrostatic image with electrostatically charged powder particles tocreate on the photoconductive insulating layer a deposit of powderparticles corresponding exactly to the electrostatic image andtransferring the powder image in image configuration to a transfermember, the improvement comprising affecting transfer of the powderimage by providing a transfer member comprising a base sheet of barytapaper ranging in thickness from 3.5 to 5.5 mils, coating said base sheetwith an elastically deformable polyisobutylene interlayer ranging inthickness from about 0.10 to about 1.0 mil selected from the groupconsisting of polyisobutylene of relatively high molecular weight and ablend of a polyisobutylene of relatively high molecular Weight with apolyethylene of a relatively low molecular weight, said interlayer beingovercoated with a resinous material ranging in thickness from about 0.10to 1.0 mil, said resinous material being substantially non-tacky at roomtemperature and selected from the group consisting of polyethylene andpolyethylene blended with microcrystalline wax, contacting the resincoating of said transfer member with the powder image on aphotoconductive insulating layer and pressing said coating and imagetogether to thereby transfer said powder image to said resin coating atsubstantially room temperature and removing said base member with itscoating from contact with said photoconductive layer whereby transfer ofthe powder particles in image configuration is achieved without thenecessity of depositing electrostatic charges on said transfer member,the pressure producing said transfer being substantially less than thatneeded when the transfer member omits said interlayer.

References Cited in the file of this patent UNITED STATES PATENTS (Otherreferences on following page) 11 12 2,543,229 Chapman Feb. 27, 1951Schafiert et a1.: Xerography: A New Principle-of 2,556,078 Francis June5, 1951 Photography and Graphic Reproduction, Journal of the 2,661,289Mayo et a1. Dec. 1, 1953 Optical Society of America, v01. 38, No. 12,December OTHER REFERENCES 1948- 5 Edelstein: Static Electricity inTextiles, American Bentzer: Baryta Paper, Paper Trade Journal, Feb. D tfi Reporter, Aug 18, 1952' 5, 1925.

UNITED STATES PATENT OFFICE Certificate of Correction Patent No.2,886,464 May 12, 1959 Warren G. Van Dorn It is hereby certified thaterror appears in the printed specification of the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 1, line 56 for valve read value; column 5, lines 20 to 35,inclusive, should read as shown helow instead of as in the patent:

Base paper 12:

Type Baryta-coated. Thickness 3.5 to 5.5 mils. Method of applying bothcoatings 11a and 11b Solution. Thickness of base coating 11a to basepaper 12 0.10 to 1.0 mil.

Thickness of overcoating 11b 0.10 to 1.0 mil. Transfer roll 29:

Material Stainless steel. Length 6 inches. Diameter- 0.75 inch.

Force applied 60 to 300 pounds.

Equivalent pressure 10 to 50 pounds per linear inch of roll length.Velocity of transfer member 10 during image transfer 2 to 4 inches persecond.

Signed and sealed this 29th day of March 1960.

Attest: KARL H. AXLINE, Attesting Ofiicer.

ROBERT C. WATSON, Commissioner of Patents.

1. IN THE XEROGRAPHIC PROCESS COMPRISING PLACING AN ELECTROSTATIC CHARGEON THE SURFACE OF A PHOTOCONDUCTIVE INSULATING LAYER, EXPOSING THEELECTRICALLY CHARGED PHOTOCONDUCTIVE INSULATING LAYER TO A PATTERN OFLIGHT AND SHADOW TO BE REPRODUCED TO CREATE THEREON AN ELECTROSTATICIMAGE CORRESPONDING TO THE PATTERN OF LIGHT AND SHADOW, CONTACTING THEELECTROSTATIC IMAGE WITH ELECTROSTATICALLY CHARGED POWDER PARTICLES TOCREATE ON THE PHOTOCONDUCTIVE INSULATING LAYER A DEPOSIT OF POWDERPARTICLES CORRESPONDING EXACTLY TO THE ELECTROSTATIC IMAGE ANDTRANSFERRING THE POWDER IMAGE IN IMAGE CONFIGURATION TO A TRANSFERMEMBER, THE IMPROVEMENT: COMPRISING AFFECTING TRANSFER OF THE POWDERIMAGE BY PROVIDING A TRANSFER MEMBER COMPRISING A BASE SHEET COATED WITHAN ELASTICALLY DEFORMABLE RESINOUS INTERLAYER OVERCOATED WITH A RESINOUSMATERIAL SUBSTANTIALLY NON-TACKY AT ROOM TEMPERATURE SELECTED FROM THEGROUP CONSISTING OF POLYETHYLENE AND POLYETHYLENE BLENDED WITH WAX,CONTACTING THE RESIN COATING OF SAID TRANSFER MEMBER WITH THE POWDERIMAGE ON A PHOTOCONDUCTIVE INSULATING LAYER AND PRESSING SAID COATINGAND IMAGE TOGETHER TO THEREBY TRANSFER SAID POWDER IMAGE TO SAID RESINCOATING AT SUBSTANTIALLY ROOM TEMPERATURE AND REMOVING SAID BASE MEMBERWITH ITS COATING FROM CONTACT WITH SAID PHOTOCONDUCTIVE LAYER WHEREBYTRANSFER OF THE POWDER PARTICLES IN IMAGE CONFIGURATION IS ACHIEVEDWITHOUT THE NECESSITY OF DEPOSITING ELECTROSTATIC CHARGES ON SAIDTRANSFER MEMBER, THE PRESSURE PRODUCING SAID TRANSFER BEINGSUBSTANTIALLY LESS THAN THAT NEEDED WHEN THE TRANSFER MEMBER OMITS SAIDINTERLAYER.